A difficult zipper makes getting dressed or packing a bag a much harder chore than it needs to be. Instead of wondering whether the zipper will cooperate and move the next time you use it, perform much-needed maintenance on it by lubricating its teeth. Waxy substances, graphite and even soap may be used to keep that zipper sliding smoothly. Use as little of the chosen lubricant as possible to help prevent stains on your zippered materials.
Wax from an unlit candle lubricates stuck zippers without creating much of a mess. Grab a loose taper candle, birthday candle or votive; any candle not stuck inside of a holder or glass will suffice. Rub the candle over the teeth of the zipper slightly above and below the slide on a stuck zipper; then jiggle the slide until it moves freely through both waxed areas. If the slide isn't stuck but just difficult to zip and unzip, rub the wax over all the teeth over the entire length of the zipper, limiting the wax to the teeth rather than over the fabric parts of the zipper or beyond the zipper area. Zip and unzip the item slowly and smoothly several times to help work the wax through the teeth. Brush off excess wax with your hand. If you do not have a candle handy, rub the corner of a dry bar of soap on the zipper instead, wiping the excess soap off with a soft cloth or paper towel afterwards.
Liquid dish soap, used as minimally as possible, lubricates stubborn or stuck zippers. Squirt a small amount of the soap onto a cotton swab; then swab the zipper teeth slightly above and below the zipper slide. Wiggle the slide through the lubricated areas; then continue lubricating the zipper teeth an inch or so at a time. Work the zipper slide over the entire length of the zipper once it has been completely lubricated with soap. Dab the excess soap off with paper towels afterwards to prevent the soap from dripping onto other areas of the zippered item.
The "lead" in a regular pencil -- actually graphite, not lead -- is a natural lubricant that's excellent for zippers of all types. Rub a somewhat dull pencil over interlocked zipper teeth; then move the slider to zip and unzip the item, working the graphite through the interlocking zipper part. Powdered graphite sold in a tube may also be used to lubricate a zipper, but it is much messier than using a pencil and may mark or stain light-colored items.
Lip balm lubricates zippers much in the same way that it lubricates lips. Select a balm that contains no lip tints, as these dyes may stain the fabric surrounding the zipper. Rub a tube-style lip balm over the zipper teeth using as little as possible at first, working the zipper slider through the lubricated area to spread the balm around. If your lip balm isn't in a tube, dip your finger or a cotton swab in the balm to apply it to the zipper teeth. Limit the balm to the toothed area of the zipper to prevent stains. Wipe away excess balm after the zipper is lubricated.